SaaS EDC systems & storing patient data

Hi,

Question about the impact of GDPR and other regulations on the use of SaaS/cloud-based EDC systems. Specifically: in the case of a multi-national trial, must patient data be stored accordance with the regulations of each patients' country of nationality. E.g., if a trial has sites in both the UK and Germany, must data collected from german subjects be stored in Germany and UK subjects in the UK?